From f3c0d86c398539ef4906023bef2f1beacb132421 Mon Sep 17 00:00:00 2001
From: Patrick Springstubbe <pat@springstubbe.us>
Date: Tue, 15 Mar 2022 12:49:29 -0400
Subject: [PATCH] add onControlOpen callback

---
 CHANGELOG             |  1 +
 README.md             | 10 ++++++++++
 jquery.multiselect.js |  6 ++++++
 3 files changed, 17 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 482b4b9..e24b787 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,7 @@
 ===================
 resolves pr#183
 resolves pr#186
+add onControlOpen callback
 
 2.4.20 (2021-12-07)
 ===================
diff --git a/README.md b/README.md
index 01cb3d0..144d745 100644
--- a/README.md
+++ b/README.md
@@ -79,6 +79,7 @@ $('select[multiple]').multiselect( 'loadOptions', [{
 | checkboxAutoFit     | bool     | false          | auto calc space requirements for checkbox instead of css padding on label |
 | onLoad              | function |                | fires at end of initial loading, hides native select list |
 | onOptionClick       | function |                | fires after on option is clicked |
+| onControlOpen       | function |                | fires when the options list is open |
 | onControlClose      | function |                | fires when the options list is closed |
 | onSelectAll         | function |                | fires when (un)select all is clicked |
 | onPlaceholder       | function |                | fires when the placeholder txt is updated |
@@ -168,6 +169,15 @@ element: select list element object
 option:  option element object
 
 
+**onControlOpen**
+
+Fires when the options list is opened
+
+`onControlOpen( element )`
+
+element: select list element object
+
+
 **onControlClose**
 
 Fires when the options list is closed
diff --git a/jquery.multiselect.js b/jquery.multiselect.js
index 8463744..e8b638c 100644
--- a/jquery.multiselect.js
+++ b/jquery.multiselect.js
@@ -70,6 +70,7 @@
         // Callbacks
         onLoad        : function( element ){},           // fires at end of list initialization
         onOptionClick : function( element, option ){},   // fires when an option is clicked
+        onControlOpen : function( element ){},           // fires when the options list is opened
         onControlClose: function( element ){},           // fires when the options list is closed
         onSelectAll   : function( element, selected ){}, // fires when (un)select all is clicked
         onPlaceholder : function( element, placeholder, selectedOpts ){}, // fires when the placeholder txt is updated
@@ -258,6 +259,11 @@
 
                 // recalculate height
                 if( optionsWrap.closest('.ms-options-wrap').hasClass('ms-active') ) {
+                    // USER CALLBACK
+                    if( typeof instance.options.onControlOpen == 'function' ) {
+                        instance.options.onControlOpen( instance.element );
+                    }
+
                     optionsWrap.css( 'maxHeight', '' );
 
                     // override with user defined maxHeight